This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A143052 #5 Mar 30 2012 18:51:00 %S A143052 0,1,3,4,2,6,7,8,9,5,11,12,13,14,15,16,10,18,19,20,21,22,23,24,25,17, %T A143052 27,28,29,30,31,32,33,34,35,36,26,38,39,40,41,42,43,44,45,46,47,48,49, %U A143052 37,51,52,53,54,55,56,57,58,59,60,61,62,63,64,50,66,67,68,69,70,71,72,73 %N A143052 Inverse permutation to A143051. %C A143052 A143054(n) = a(a(n)); %C A143052 a(A005563(n)) = A000290(n+1) for n>0; %C A143052 a(A000290(n)) = A002522(n-1) + 1 for n>0. %H A143052 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %K A143052 nonn %O A143052 0,3 %A A143052 _Reinhard Zumkeller_, Jul 20 2008